Pattern perception and organization provide the representations that form the basic processing units in the visual cognition system of adults. The overall aim of the proposed research is to investigate the origins and development of such perceptual organization abilities in infants. Specifically, we are concerned with the very beginnings of perceptual unit formation and the operation of a variety of organizational principles during the first months of life. The research proposal describes a number of experiments that rely on visual preference procedures to study the organization of arrays of visual elements by young infants. The experiments seek to determine: (1) Which grouping principles lead to organized representations of visual pattern information? (2) Do some principles consistently take precedence over others, thereby suggesting a hierarchy of rule use in the development of perceptual organization? (3) Can the principles work in an additive fashion, thus suggesting a kind of threshold model for perceptual unit formation? (4) What is the time course of development for each of the various principles? Are the individual principles yoked or do they have independent developmental trajectories? And (5) What are the developmental factors (i.e., maturation, experience) that affect the emergence of the different grouping principles? The significance of the proposed research is that it will provide knowledge about how perceptual units are formed, their nature, and their ontogenesis as well as how representations of visual pattern information by adults arise from the perceptual units of infants. In short, this research will inform us about the formation of the coherent representations of visual patterns that form the basic functional units of human cognition. Knowledge about the development of this fundamental mental ability will also provide insights into understanding deviations from the normal course of perceptual-cognitive development. [unreadable] [unreadable]